Pain is the most common symptom of disease and a frequent long term complication to many diseases. Nociceptive pain (occurring from any body damage) may be treated with pharmaceutical drugs whereas neurogenic pain occurring from damage to either the peripheral or the central nervous system is often difficult to treat with medication. Scientific brain mapping studies with magnetic resonance imaging (MRI) and positron emission tomography (PET) have shown that that the central pathways and cortical representation of the sensory system is almost congruent for painful stimuli and vibrotactile stimuli.
It is known that sound wave stimulation can help relieving pain by activating/blocking the areas of the brain that otherwise deliver the pain perception. The hypothesis that such afferent stimulation can reduce the perceived pain is based on both scientific discoveries and experience. In 1950-54 the neurophysiologist Amassian discovered that simultaneous stimulation of the Nn. Splanchnici (afferent nerves from the abdominal cavity) and N. Ulnaris (from the arm) leads to a decrease of the amplitude registered in the S2 area of the brain (which receives all afferent impulses and is responsible for the detection and location of sensitive inputs) compared to the amplitude when N. Ulnaris is stimulated alone. This discovery provides the theoretical basis for reducing the perceived somatic pain by generating afferent impulses to Nn. Splanchnici.
The Pacinian corpuscles (mechanoreceptors capable of detecting pressure/vibration) send afferent impulses through thick, well myelinated nerve fibres resulting in impulses propagating through the nervous system with maximal amplitude and velocity. They are particularly susceptible to vibrations and pressure and located in the skin and various internal organs. The Pacinian corpuscles in the skin respond to frequencies below 600 Hz and are most sensitive to vibrations around 250 Hz.